Nicotinamid adenine dinucleotides exist in two forms, both of which are used in assaying biological materials. The reduced or hydrogenated form is known as NADH, and the oxidized or dehydrogenated form used in this invention is known as NAD.
Both NAD and NADH are unstable and deteriorate rapidly if kept in the presence of water under ordinary conditions. Consequently, it has been the practice until recently to keep such materials in the absence of water, in a completely dry solid condition.
It is now known that NADH can be kept at room temperature without deterioration if the pure material is dissolved in essentially anhydrous glycol, especially if a small amount of an amine or other alkaline material is present. However NAD is not sufficiently stable if treated in the same manner, particularly not if kept alkaline.